Videopad audio and movie out of sync

[Katie11111]

I have started making asmr and had to record and film separately due to the mic being too powerful for my phone. 
so I filmed on my phone and recorded On audacity and had both ready And saved to create into one video however I have put them together and at the beginning the audio is almost perfectly in sync but quickly into the film the audio is really far behind, I have no idea how this even works or how to fix it, I’ve been reading up for hours but I just don’t know what to do. Any help would be appreciated